When Yahoo said on Thursday that data from at least 500 million user accounts had been hacked, it wasn’t just admitting to a huge failing in data security — it was admitting to the biggest hack the world has ever seen.

Until Thursday, the previous largest known hack was the 2008 breach that hit almost 360 million MySpace accounts, according to a ranking by the “Have I been pwned” website. Like the Yahoo breach, the hack was only publicly disclosed this year after data was offered on a hacker forum.

And only three breaches had ranked above the 100 million level:

LinkedIn reported a loss of 167 million email addresses and passwords. They were originally stolen in 2012 but not publicly disclosed until 2016, again after the data was offered on an underground “dark market” site.

A 2013 hack of Adobe saw 153 million account details lost. They included user names, email addresses, and encrypted passwords, but the encryption was poorly implemented and reversed on some accounts.

And there’s been a reported but unverified hack of dating website Badoo. Data including email addresses, names, and passwords for about112 million members was found online.

The LinkedIn and MySpace data sets, along with 200 million Yahoo records, were put up for sale by the same hacker, peace_of_mind.

Major hacks can turn out to be a headache for users, even if the data is old and the account in question is no longer used. That’s because many people use the same password or a similar password across services, so a successful hack of Yahoo could expose an email address and password that would work on other sites.

And if you think the numerous, continuous hacks of major websites have pushed people to exercise better password security, consider this. These are the top 10 passwords associated with the 153 million hacked Adobe accounts and the number of accounts that used then.